Potential flows about airfoils/hydrofoils with one- and two-way coupled boundary layer models

Abstract

The main objectives of this thesis are to implement the one- and two-way couplings of an inviscid flow formulation with an appropriate boundary layer model and to verify and benchmark the implementations against experimental results. The coupling between the boundary layer and the inviscid formulation allows a quick calculation of the most important aerodynamic/hydrodynamic coefficients, i.e., lift and drag coefficients. There are two possibilities when coupling inviscid formulations with boundary layer models: one- and two-way couplings. One-way coupling model neglects the effect of the boundary layer thickness on the body itself, i.e., the modification of the shape that the flow sees. In one-way coupling, the initial tangential velocity distribution along the body coming from the inviscid model is used for the computation of the boundary layer and subsequently the calculation of drag. In two-way coupling, the boundary layer thickness, which is computed in the boundary layer model, modifies the shape of the airfoil used in the inviscid model and a second computation of the tangential velocities around the modified body is performed. The procedure is repeated till we achieve the required convergence. Obviously, two-way coupling is generally expected to produce more accurate results.